Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems (e.g., a Long Term Evolution (LTE) system).
Generally, a wireless multiple-access communications system may include a number of base stations, each simultaneously supporting communication for multiple mobile devices or other user equipment (UE) devices. Base stations may communicate with UEs on downstream and upstream links. Each base station has a coverage range, which may be referred to as the coverage area of the cell. A UE may both receive data from a base station (downlink) and transmit data to a base station (uplink).
In certain deployments it may be advantageous to have relatively large cells. For example, a system may operate to provide for Internet communication to aircraft by terrestrial air-to-ground (ATG) systems. In such cases, due to the altitude and speed at which an aircraft may travel, it may be desirable for cells within the system to have an expanded coverage area relative to a cell coverage area for terrestrial-based UEs. In such examples, propagation delay between a UE and a base station may become a significant portion of a radio frame that may be used for transmission of data. For example, if a system utilizes one millisecond subframes, a propagation delay that exceeds one millisecond may result in arrival of a subframe outside of a subframe boundary at a receiver. In some systems, a propagation delay of about 670 μs may be supported, with any propagation delay in excess of that limit not being supported. In order to provide a system that supports such relatively large cells and allows communications according to such established protocols, it may be desirable for systems to operate in environments in which a propagation delay may exceed a propagation delay limit associated with the wireless communications network.